Rotary Nutating engine

ABSTRACT

The engine comprises a housing having a spherical chamber containing a pair of segmental-spherical members having confronting recessed operating faces. One member, the stator, is fixed and has in its face a pair of opposed, radially projecting, segmental-conical recesses separated by a pair of curved, segmental-conical ribs, the apices of which lie in a common plane extending diametrally through the stator. The other member, the rotor is journaled in the inner end of a crankshaft which projects into the housing coaxially of the stator, and has in its face three, radially projecting, segmental-conical recesses separated by three-equi-angularly spaced ribs having linear apices, which project radially from the axial centerline of the rotor. The rotor is rotatable about an axis inclined to the crankshaft, and at a different speed than the crankshaft. Therefore, when the crankshaft rotates, nutating rotary motion is imparted to the rotor so that its ribs follow the recessed face of the stator without imparting any reciprocable motion to either. Ports in the stator and/or housing are used to supply fluid or fuel to, and to exhaust compressed fluid from, revolving pockets which are formed by the recesses in the rotor during operation of the engine as either a fluid pump or engine, or as an internal combustion engine.

United States Patent Wahl July 22, 1975 ROTARY NUTATING ENGINE chambercontaining a pair of segmental-spherical [76] Inventor: Robert H. wahl,1747 Creek Rd" members having confronting recessed operating faces.Rochester NY. 14625 One member, the stator, is fixed and has in its facea pair of opposed, radially pro ecting, segmental-conical [22] Filed:May 17, 1974 recesses separated by a pair of curved, segmentalconicalribs, the apices of which lie in a common [21] Appl' 470860 planeextending diametrally through the stator. The other member, the rotor isjournaled in the inner end [52] US. Cl l23/8.45; 4] 8/49 of a crankshaftwhich projects into the housing coaxi- Fozb 53/00 ally of the stator,and has in its face three, radially [58] Field Of Search 123/845;projecting, segmental-conical recesses separated by 4 68three-equi-angularly spaced ribs having linear apices,

- which project radially from the axial centerline of the ReferencesCited rotor. The rotor is rotatable about an axis inclined to UNITEDSTATES PATENTS the crankshaft, and at a different speed than the3,464,361 9/1969 Voser 418/68 crankshaft Theefme when the Crankshaftrotates 3,485,218 12/1969 Clarke 418/53 mutating rotary motion isimparted to the rotor 89 that 3,492,974 2 1970 Kreimeyer 418/53 its ribsfollow the recessed face of the st ut Primary ExaminerWilliam L. FreehAssistant Examiner-Michael Koczo, Jr.

Attorney, Agent, or Firm-Shlesinger, Fitzsimmons & Shlesinger [57]ABSTRACT The engine comprises a housing having a spherical 9 Claims, 7Drawing Figures ROTARY NUTATING ENGINE This invention relates to rotarynutating devices, and more particularly to a nutating engine of the typehaving a stator and nutating rotor, and operable selectively as a motoror pump.

l-leretofore efforts have been made to provide a nutating engine of thetype in which two segmental sections of a spherical body are rotated onerelative to the other to compress a fluid between the confronting,recessed faces thereof. A major disadvantage of most such prior engines,however, is that one of these two sections of the engine i.e., eitherthe rotor or the stator must be mounted for linear reciprocable movementrelative to the other section.

It is an object of this invention to provide a novel nutating engine inwhich neither the rotor nor stator section thereof is mounted for linearreciprocable motion.

Another object of this invention is to provide a nutating engine of thetype described in which the rotor section of the engine is mountedsolely for rotary nutating motion relative to the stator section of theengine.

A further object of this invention is to provide an improved nutatingengine, which is substantially less complicated and inexpensive tomanufacture than prior such engines.

Other objects of the invention will be apparent hereinafter from thespecification and from the recital of the appended claims, particularlywhen read in conjunction with the accompanying drawings.

IN THE DRAWINGS FIG. 1 is a fragmentary, side elevational view of anengine made according to one embodiment of this invention, portions ofthe engine and its housing being broken away and shown in section forpurposes of illustration;

FIG. 2 is a plan view of the rotor which forms part of this engine;

FIG. 3 is a sectional view taken along the line 33 in FIG. 2 looking inthe direction of the arrows;

FIG. 4 is a side elevational view of the stator, which forms part ofthis engine;

FIG. 5 is a bottom plan view of the stator;

FIG. 6 is a plan view of a modified form of stator that may be used withthis invention; and

FIG. 7 is a fragmentary side elevational view similar to FIG. 1, butshowing a modified form of rotor that may be used with this engine.

Referring now to the drawings by numerals of reference, and first to theembodiment illustrated in FIGS. 1 to 5, l denotes generally an enginecomprising a housing 11 having therein a central, segmentalsphericalchamber 12. This chamber opens at its lower end of a circular recess 13,which is formed in the bottom of housing 11, and at its upper end on areduceddiameter bore 14 that is formed in the upper end of the housingcoaxially of chamber 12' and recess 13. Housing 11, which may be formedfrom two, like, separable sections that are releasably and sealingsecured together by any conventional means, may be closed at its lowerend by a bottom plate 16, and at its upper end by a cover plate 17.

Secured in the upper end of chamber 12 coaxially thereof is asegmental-spherical stator 21 (FIGS. 1, 4 and having an axial centerlinedenoted at Y-l, and a plane upper surface 22, which registers coaxiallywith the bore 14. The stator 21 is designed so that the center of itsspherical surface is common with that of chamber 12. At its opposite orlower end (FIGS. 1 and 4) diametrally opposite sides of stator 21 arescalloped out or recessed to form therein opposed, generallysegmentalconical hollows or recesses 23 and 24, which radiate from acommon point Xl (FIG. 5) on axis Y-l. The recesses 23 and 24 areseparated by aligned, segmentalconical ribs having aligned apices 25 and26 which also extend to point Xl.

Intermediate its ends the stator 21 has therethrough an axial bore 27which opens at its upper end on the surface 22, and at its lower end onthe recess 23 immediately adjacent the apex 26. Two additional axialbores 28 and 29 are formed in the stator 21 to open at their upper endson the surface 22, and at their lower ends on opposite sides,respectively, of the other apex 25 of the stator for a purpose to benoted hereinafter.

Numeral 31 (FIGS. 1 to 3) denotes the engine rotor. which also forms asegment of a sphere having the same diameter as the chamber 12 and thestator 21. The rotor has a plane, circular underside 32 disposedcoaxially of the rotor axis Y-2 and lying in a plane extending normal tothis axis. In its upper end rotor 31 has three, equi-angularly spacedhollows or recesses 33, 34 and 35, which are generally segmental-concialin configuration, and which radiate from a common point X2 on the rotoraxis Y-2. These recesses are separated by the three equi-angularlyspaced crests or apices 36, 37 and 38, each of which forms a straightline which is inclined from its upper end downwardly to the point X2 onthe rotor 31.

The rotor 31 is mounted in chamber 12 beneath the stator 21 with itsrecessed upper surface confronting the recessed, lower surface of thestator. A spur gear 41 is secured to the underside 32 of the rotorcoaxially of its axis Y-2 by a plurality of screws 42, or the like. Astub shaft 43, which is integral with the bottom of the rotor, projectscoaxially through an axial bore in the gear 41, and rotatably into aregistering recess 44 formed in the confronting surface of a mountingplate 45, which is integral with the upper end of the engine drive orcrank shaft 46. Shaft 46 projects rotatably through a central opening47, which is formed in plate 16 coaxially of the chamber Y-l.

Mounted intermediate its ends to rotate in the plate 45 in spaced,parallel relation to shaft 43 is a further shaft 50. Secured coaxiallyto opposite ends of the shaft 50 for rotation in spaced, parallel planesabove and below, respectively, the plate 45 are two gears 51 and 52.Gear 51 meshes with the gear 41; and gear 52 meshes with an annularbevel gear 53, which is secured by screws 54 to the inside surface ofthe plate 16 coaxially of shaft 46.

Referring now to FIG. 1, A denotes the angle that is formed between eachof the three rotor apices 36, 37 and 38 and the plane bottom surface 32of the rotor, and by way of example may be 15. Angle B denotes the angleof inclination of the rotor axis (stub shaft 43) to the axis of theengine shaft 46, and is equal to angle A in the illustrated embodiment.Angle C represents the inclination of apex 38 to the horizontal at anygiven instant, and of course will vary depending upon the angularposition of the rotor 31 relative to the stator 21.

For example, in FIG. 1 the stator 21 is shown from its position asillustrated in FIG. 4, so that its re-' cess 23 faces toward the right,and so that its aligned apices 25 and 26 appear in FIG. 1 as a pointregistering with the intersection of axes Y-l and Y-2. The rotor 31, onthe otherhand, has the same angular position as in FIG. 2 (i.e., theapex 38 extends toward the right),

but its axis Y-2 is inclined by the angle B to the axis Y-l of thestator so that the rotor apex 38 is in linear contact with the recess 23in the stator along a line ex tending between the point X-l and theuppermost point (FIG. 1) in recess 23. Also at this time the other twoapices 36 and 37 of the rotor have linear contact with the recess ordwell section 24 of the stator adjacent opposite ends thereof. Thesethree lines of contact between the rotor and stator, as represented bythe rotor apices 36, 37 and 38, are angularly spaced from each other 120about the axis Y-2, and as noted hereinafter, rotate about the axis Y-2and nutate about Y-l, when the rotor is nutating.

FIG. 1 shows angle C at a maximum value. The gearing 41, 51, 52 and 53,is selected to cause the shaft 46 to rotate three revolutions for everyone revolution of the rotor 31. Therefore, whenever the rotors apices36, 37 and 38 are rotated 90 relative to the stator 21 (for example fromthe point in FIG. 1 where the apex 38 registers with the center ofrecess 23 to a point where the former registers with the stator apex 25)the shaft 46 will rotate 270 about its axis, or 180 relative to therotor 31. During this 180 change in relationship between the rotor 31and the shaft 46 the rotor apices do follow the contour of the stator,so that angle C will be decreased to approximately zero as apex 38passes beneath the center of rib 25. This action, which imparts nutatingmotion to the rotor, is made possible because the rotor 31 contains arecess 33, 34 or 35 directly opposite, or 180 from, each of its apices37, 38 and 36, respectively. Consequently, whenever any one of the rotorapices registers with one of the stator apices, a recess 33, 34 or 35 inthe rotor registers with the opposite high point or apex on the stator.Moreover, as the rotor revolves, the three, angularly spaced lines ofcontact defined by the apices 36, 37 and 38 divide the chamber 12between the rotor and stator into three, spaced pockets (two of whichare denoted at P1 and P2 in FIG. 1), which vary in size andconfiguration as the rotor revolves.

When used as an internal combustion engine, and assuming that the rotor31 rotates clockwise in FIG. 2 ia indicated by the arrow, two pipes ortubes 61 and 62 may be used to connect the bores or ports 28 and 29 inthe stator to an exhaust system and to a fuel supply, respectively.Means for igniting the fuel, such as spark plug 63 (FIGS. 4 and may bemounted in the bore 27 in the stator and connected in known manner to apower supply. When the shaft 46 is rotated by a conventional startingmechanism (not illustrated), the rotor 31, as illustrated in FIG. 1,will continue to compress the contents of pocket P1 until the lowestpoint of the recess 33 has passed beneath the apex or high point 25 onthe stator 21.. During this interval the exhaust port 28 is opened, andthe pocket Pl diminishes in size until it reaches its smallest volume,so that any gas previously contained in the pocket P1 is exhausted outof the duct 28.

As soon as the lowest point of recess 33 passes beneath the stator apex25, the pocket P1 begins to increase in volume, and also begins to drawinto the pocket a fuel-air mixture from the fuel supply port 29..

During this movement pocket P1 revolves toward the position previouslyoccupied by the pocket P2 (FIG. 1)

and increases in size as the rotor apex 36 approaches the apex 26 on thestator. After the apex 36 passes beneath the apex stator 26, the pocketP1 begins again to diminish in size, so that its contents (the fuel-airmixture) is compressed as the rotor recess 33 passes beneath the statorapex 26. When the lowest point of the recess 33 has passed beneath andslightly beyond the stator apex 26, the spark plug 63 is energized toignite the now-compressed fuel-air mixture in the compressed pocket Pl,so that this mixture expands rapidly to provide the power which drivesthe rotor. The ignited mixture continues to expand, and the pocket Plbecomes larger as the rotor recess 33 rotates beneath the recess ordwell portion 23 of the stator. As the low point of recess 33 passesbeneath the center of thc dwell 23 on the stator, the rotor apex 36passes beneath the inner end of the port 28 on the stator to open thisexhaust port so that the burned fuel in the pocket P1 is now exhaustedout of the port 28 as the rotor recess 33 once again passes beneath thestator apex 25 as described,

above. This completes one revolution of the rotor 31 relative to thestator 21 From the foregoing it will be apparent that each of the threerecesses 33, 34 and 35 in the rotor forms part of successive compressionand expansion operations as it passes beneath each stator. apex 25 and26. At any point during the operation of the engine, moreover, each ofthe three rotor recesses 33, 34 and 35 is working at some phase of thecombustion process; and at all times, the linear contact between thethree rotor apices 36, 37 and 38 and the confronting surfaces on thestator 21 operate to maintain the three corresponding pockets P1, P2,etc. sealed off from each other so that while a fuel-air mixture may beexpanding in one pocket (for example P2 in FIG. 1), a previously burnedmixture may be in a compression stage in the following pocket (forexample P1 in FIG. 1).

Instead of operating as an internal combustion engine, 10,alternatively, could be employed as a fluid pump, in which case theshaft 46 would be driven by an external source. In such case a modifiedstator of the type denoted at 21 in FIG. 6 could be employed. Thisstator is similar to the above-described stator 21, ex-

cept that the spark plug bore 27 has been replaced by two, spaced,parallel, axially extending bores 28' and 29', which open on oppositesides of the apex 26 to function in a manner similar to the bores 28 and29.

In use, and assuming the rotor 31 is driven in the same direction asdescribed in connection with the first embodiment, the bores 29 and 29would be connected to a fluid supply, while the bores 28 and 28' wouldbe connected to a fluid pressure system, or the like. Then, as eachrecess in the rotor 31 passes beneath one of the stator apices 25 or 26,the fluid in the associated pocket would first be compressed and forcedout of one of the bores 28 or 28' to the associated pressure system, andthereafter, as soon as the pocket again began'to expand, fluid would bedrawn into the expanding pocket from one of the supply bores 29 or 29'.

For example, referring to FIG. 1, and assuming that the engine 10 weredesigned withthe modified stator 21 to function as a pump, as the pocketP1 rotates beneath the stator apex 25, the fluid in the pocket would.

be compressed out of the bore 28 until the low point on the recess 33passed beneath the high point of the apex 25 on the stator. Thereafterpocket Pl would again being to expand and fluid would be drawn into thepocket from the bore 29, and would subsequently be compressed anddischarged out of the bore 28 as the recess 33 passed beneath the otherstator apex 26.

In FIG. 7, wherein like numerals are employed denote elements similar tothose in the first embodiment, 31 denotes a modified rotor, which may beused in combination with the stator 21 in a modified engine At its lowerend the rotor 31' has a central, circular recess 70, which surrounds areduced-diameter stub shaft 71, which is integral with the underside ofthe rotor coaxially of its axis Y-2. Shaft 71 is rotatably journaled ina bearing 72, which is secured in a circular recess or pocket 73 that isformed in an enlargeddiameter collar 74 that is integral with the innerend of the engine shaft 46. Collar 74 projects into the recess 70 abovea bevel gear 53, which, as in the first embodiment, is secured on theinside of the base plate 16. The teeth of the bevel gear 53 mesh withthe teeth of a ring gear 76, which is secured to the bottom of the rotor31 coaxially of its recess 70.

Engine 10' is otherwise similar in configuration to the previouslydescribed engine, the modified gearing being such that the rotor 31'makes one revolution for each three revolutions of the shaft 46. Thisgives the rotor 31 the necessary motion to follow the sinuousconfiguration of the stator 21. By way of example, the ring gear 76 mayhave thereon fifty-one teeth, while the bevel gear 53 may have thereonthirty-four teeth. While the number of teeth may be varied, dependingupon the size of the engine, the ratio should be maintained the same inorder to produce the desired motion.

From the foregoing it will be apparent that the instant inventionprovides an extremely efficient and compact engine suitable for useselectively as an internal combustion engine or as a compression pump.While only a single fuel supply and a single exhaust port have beenillustrated in the embodiment shown in FIGS. 1 to 5, it will be apparentthat additional such ports can be used, if desired, and their placementcan be varied. They may even be placed, for example, in the housing 11.Moreover, the engine (l0, 10') may, if desired, be diesel or glowwithout, therefore, requiring the use of a spark plug. In addition theengine could be operated as a fluid motor, in which case fluid underpressure could be applied through orifices at the bores 29 and 29' (FIG.6), which would force expansion of the associated pockets P1, P2 etc. toimpart the driving force for the motor; and the bores 28 and 28', would,in such case, function as the exhaust ports, to allow evacuation of thefluid from the pockets.

Also, while the stator has been described as being a part separated fromthe housing 11, it could be made integral therewith if desired.Furthermore, it will be apparent that the number of recesses in thefaces of the stator and rotor may be increased, if desired, provided thenumber of recesses in one of them exceeds by one the number of recessesin the other, and provided also a corresponding change is made in thegearing which produces relative rotation between the rotor and thecrankshaft. Also, the apices of the ribs in the stator face could beother than aligned, provided, of course, a corresponding compensation ismade in the inclination of the rotor ribs to the rotor axis.

While only certain embodiments of this invention have been illustratedand described in detail herein, it will be apparent that thisapplication is intended to cover any such modifications of the inventionwhich may fall within the scope of one skilled in the art, and theappended claims.

Having thus described my invention, what I claim is:

1. An engine, comprising a housing having therein a spherical chamber,

a solid, segmental-spherical rotor movably mounted in said chamberadjacent one end thereof and having a solid operating surfaceconfronting a stationary operating surface formed in said chamberadjacent the opposite end thereof, said operating surfaces havingcenters which coincide with the center of said chamber,

each of said operating surfaces having therein a plurality of generallysegmental-conical recesses emanating radially from the center of thesurface and forming thereon a plurality of equi-angularly spaced ribswhich project radially between said recesses from adjacent thelast-named center to points immediately adjacent to the spherical wallof the chamber,

a shaft supported in said housing adjacent one end there and extendingpart way only into said chamber at said one end thereof and rotatableabout a first axis extending through the center of said chamber,

means mounting said rotor on the inner end of said shaft for rotationrelative to said shaft about a second axis extending through the centerof said chamber and inclined to said first axis, and for rotation withsaid shaft about said first axis, and

connecting means between said shaft and said rotor for causing saidshaft to revolve three times about said first axis for each revolutionof said rotor about said second axis, thereby to impart rotary andnutating motion to said rotor to maintain said ribs on the operatingsurface of said rotor in sliding engagement with the stationaryoperating surface, whereby a plurality of revolving pockets are formedbetween said operating surfaces and the wall of said chamber andalternately expand and contract during rotation of said rotor and saidshaft.

2. An engine as defined in claim 1,wherein there are three of saidrecesses in the operating surface of said rotor separated by three ribsthe apices of which are inclined to each other and to said first axis,

there are two of said recesses in the stationary operating surfaceseparated by a pair of ribs having apices extending transverse to saidfirst axis, and

the angle of inclination of the apex of each of said three ribs on saidrotor is equal to the angle of inclination of said second axis to saidfirst axis.

3. An engine as defined in claim 1, wherein said shaft projectsexteriorly of said housing, and

said connecting means between said shaft and said rotor is operativeupon rotation of said shaft to impart relative rotation to said rotorand vice versa.

4. An engine as defined in claim 3, wherein said connecting meanscomprises a first gear fixed to said housing coaxially of said shaft,and a second gear fixed to said rotor and meshing with said first gearto effect said relative rotation between said shaft and said rotor.

5. An engine as defined in claim 3, wherein said connected meanscomprises a first gear fixed to said housing coaxially of said shaft.

a second gear secured to said rotor coaxially of said second axis, and

a pair of planetary gears interposed between said first and second gearsand operative to effect said rela tive rotation between said shaft andsaid rotor.

6. An engine as defined in claim 5, including a stub shaft projectingfrom said rotor rotatably into a cylindrical recess formed in one end ofthe firstnamed shaft coaxially of said second axis, and

an idler shaft rotatably mounted in said one end of said first-namedshaft to rotate in spaced, parallel relation to said stub shaft,

said planetary gears being secured to opposite ends of said idler shaftand meshing with said first and second gears, respectively.

7. An engine as defined in claim 1, including means in said housing forconveying fluid to each of said pockets during the expansion thereof,and for exhausting said fluid from said pockets to the exterior of saidhousing during the contraction of said pockets.

8. An engine as defined in claim 1, including means in said housing forsupplying fuel to each of said pockets during alternate expansion stagesthereof, thereby to effect compression of said fuel upon the alternatecompression stages of each pocket which follow said alternate expansionstages thereof,

means for igniting the compressed fuel in said pockets at thecommencement of the intervening expansion stages of the pockets, and

means in said housing for exhausting burned fuel from said pocketsduring the intervening compression stages thereof, which follow saidintervening expansion stages.

9. An engine, comprising a housing having therein a segmental-sphericalcham ber,

a shaft rotatably mounted intermediate its ends in one end of saidhousing, and having an inner end projecting part way only into saidchamber,

a stator fixed in said chamber opposite said shaft and having anoperating surface the center of which coincides with the center of thesphere of which said chamber is a segment, i

a segmental-spherical rotor in said chamber between said stator and saidshaft and having an operating surface confronting the operating surfaceof said stator, and having its center coinciding with the center of saidsphere,

said stator having in its operating surface a pair of equi-angularlyspaced, generally segmental-conical recesses emanating from the centerof the stator operating surface and forming thereon a pair of generallysegmental-conical ribs projecting radially from its center between saidrecesses,

said rotor having in its operating surface three equiangularly spaced,generally segmental-conical recesses emanating from the center of therotor operating surface and forming thereon three equiangularly spacedribs having linear apices extending radially outwardly from the centerof the rotor operating surface, and

means mounting said rotor on said inner end of said shaft for rotary,nutating movement about the center of said stator operating surface,thereby to maintain the apices of said ribs on said rotor in slidingcontact with the operating surface of said stator during said movement,

said mounting means including means connecting said shaft to said rotorto impart relative rotation therebetween at a rate of threee revolutionsof said shaft for each revolution of said rotor.

1. An engine, comprising a housing having therein a spherical chamber, asolid, segmental-spherical rotor movably mounted in said chamberadjacent one end thereof and having a solid operating surfaceconfronting a stationary operating surface formed in said chamberadjacent the oppoSite end thereof, said operating surfaces havingcenters which coincide with the center of said chamber, each of saidoperating surfaces having therein a plurality of generallysegmental-conical recesses emanating radially from the center of thesurface and forming thereon a plurality of equi-angularly spaced ribswhich project radially between said recesses from adjacent thelast-named center to points immediately adjacent to the spherical wallof the chamber, a shaft supported in said housing adjacent one end thereand extending part way only into said chamber at said one end thereofand rotatable about a first axis extending through the center of saidchamber, means mounting said rotor on the inner end of said shaft forrotation relative to said shaft about a second axis extending throughthe center of said chamber and inclined to said first axis, and forrotation with said shaft about said first axis, and connecting meansbetween said shaft and said rotor for causing said shaft to revolvethree times about said first axis for each revolution of said rotorabout said second axis, thereby to impart rotary and nutating motion tosaid rotor to maintain said ribs on the operating surface of said rotorin sliding engagement with the stationary operating surface, whereby aplurality of revolving pockets are formed between said operatingsurfaces and the wall of said chamber and alternately expand andcontract during rotation of said rotor and said shaft.
 2. An engine asdefined in claim 1,wherein there are three of said recesses in theoperating surface of said rotor separated by three ribs the apices ofwhich are inclined to each other and to said first axis, there are twoof said recesses in the stationary operating surface separated by a pairof ribs having apices extending transverse to said first axis, and theangle of inclination of the apex of each of said three ribs on saidrotor is equal to the angle of inclination of said second axis to saidfirst axis.
 3. An engine as defined in claim 1, wherein said shaftprojects exteriorly of said housing, and said connecting means betweensaid shaft and said rotor is operative upon rotation of said shaft toimpart relative rotation to said rotor and vice versa.
 4. An engine asdefined in claim 3, wherein said connecting means comprises a first gearfixed to said housing coaxially of said shaft, and a second gear fixedto said rotor and meshing with said first gear to effect said relativerotation between said shaft and said rotor.
 5. An engine as defined inclaim 3, wherein said connected means comprises a first gear fixed tosaid housing coaxially of said shaft. a second gear secured to saidrotor coaxially of said second axis, and a pair of planetary gearsinterposed between said first and second gears and operative to effectsaid relative rotation between said shaft and said rotor.
 6. An engineas defined in claim 5, including a stub shaft projecting from said rotorrotatably into a cylindrical recess formed in one end of the first-namedshaft coaxially of said second axis, and an idler shaft rotatablymounted in said one end of said first-named shaft to rotate in spaced,parallel relation to said stub shaft, said planetary gears being securedto opposite ends of said idler shaft and meshing with said first andsecond gears, respectively.
 7. An engine as defined in claim 1,including means in said housing for conveying fluid to each of saidpockets during the expansion thereof, and for exhausting said fluid fromsaid pockets to the exterior of said housing during the contraction ofsaid pockets.
 8. An engine as defined in claim 1, including means insaid housing for supplying fuel to each of said pockets during alternateexpansion stages thereof, thereby to effect compression of said fuelupon the alternate compression stages of each pocket which follow saidalternate expansion stages thereof, means For igniting the compressedfuel in said pockets at the commencement of the intervening expansionstages of the pockets, and means in said housing for exhausting burnedfuel from said pockets during the intervening compression stagesthereof, which follow said intervening expansion stages.
 9. An engine,comprising a housing having therein a segmental-spherical chamber, ashaft rotatably mounted intermediate its ends in one end of saidhousing, and having an inner end projecting part way only into saidchamber, a stator fixed in said chamber opposite said shaft and havingan operating surface the center of which coincides with the center ofthe sphere of which said chamber is a segment, a segmental-sphericalrotor in said chamber between said stator and said shaft and having anoperating surface confronting the operating surface of said stator, andhaving its center coinciding with the center of said sphere, said statorhaving in its operating surface a pair of equi-angularly spaced,generally segmental-conical recesses emanating from the center of thestator operating surface and forming thereon a pair of generallysegmental-conical ribs projecting radially from its center between saidrecesses, said rotor having in its operating surface threeequi-angularly spaced, generally segmental-conical recesses emanatingfrom the center of the rotor operating surface and forming thereon threeequi-angularly spaced ribs having linear apices extending radiallyoutwardly from the center of the rotor operating surface, and meansmounting said rotor on said inner end of said shaft for rotary, nutatingmovement about the center of said stator operating surface, thereby tomaintain the apices of said ribs on said rotor in sliding contact withthe operating surface of said stator during said movement, said mountingmeans including means connecting said shaft to said rotor to impartrelative rotation therebetween at a rate of threee revolutions of saidshaft for each revolution of said rotor.